Petitioner (noun)

1. A person who makes a request or petition, especially to a government or official body.
2. A person who presents a formal request or plea to a court or other judicial body.
3. A person who makes a request or petition to a governing body or authority.

Origin:

From latin petitio (a request), from petere (to seek).

Examples:

1. The petitioner made a request for a new trial.
2. The petitioner presented evidence to support their claim.
3. The petitioner asked the court to grant them a divorce.
4. The petitioner submitted a petition with thousands of signatures.
5. The petitioner sought a resolution to the issue through a formal petition.